There is an optical control device including: a semiconductor laser which generates a laser beam according to a drive current; a light amount detecting unit that detects a light amount of the laser beam generated by the semiconductor laser; and a controller that controls the drive current so as to adjust the light amount to a target value by referring to the light amount detected by the light amount detecting unit. In this type of optical control device, the light amount of a laser beam generated by the semiconductor laser can be adjusted to the target value.
For this type of device, to eliminate droop characteristics and noise of the semiconductor laser, JP-A-7-125305 discloses that every light amounts obtained by unblanking APC in the first line are stored and every values including values obtained by the APC at the beginning are averaged and the average is set as a light amount set value for the second line.
However, if the above-described control according to JP-A-7-125305 is performed when the drive current starts flowing, the light amount change is made less distinct and the time until the light amount reaches the target value becomes long.
An optical control device includes a switching unit that draws the drive currents into an energizing path that does not pass through the semiconductor laser. In the optical control device, even when the semiconductor laser to be turned off, the drive current is made to flow into the semiconductor laser by the switching unit at a time when the semiconductor laser emits light without influence on other devices, in order to detect a light amount to be referred. However, the light amount immediately after the drive current made to flow into the semiconductor laser is unstable due to fluctuation such as overshoot. However, in some cases, it is difficult to continue emitting light from the semiconductor laser until the light amount becomes stable. If the drive current is controlled by referring to the light amount detected in a period in which the light amount is unstable as described above, there is a possibility that the light amount of the laser beam generated from the semiconductor laser cannot be satisfactorily controlled to the target value.